Process for removing gum-forming and color-imparting bodies from cracked unsaturated hydrocarbon oils



NOV. 14, 1939. 5 R Q OSTERSTRQM 1 2,180,324

PROCESS FOR REMOVING GUM-FORMING AND'COLOR-IMPARTING BODIES FROM CRACKED UNSATURATED HYDROCARBON OILS Filed March 7, 1932 772411 713 Fuller; fieai'ing v anIC l lzllers d'eparaling Tower Pressure fieducin;

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Patented Nov. 14, 1939 PATENT OFFICE Y PROCESS FOR REMOVING GUM-FORMING AND COLOR-MARTING BODIES FROM CRACKED UNSATURATED HYDROCAR- BON OILS Rudolph C. Osterstrom, Chicago, 'Ill., assignor to The Pure Oil Company, Chicago, Ill., a corporation of Ohio Application March 7,1932, Serial No. 597,140

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This invention relatesto an improved process for treating cracked low boiling unsaturated hydrocarbon oils for 'the purpose of substantially removing from such oils gum-forming and color imparting compounds, whereby to render the treated oils suitable for use as improved fuels for internal combustion engines.

Low boiling motor fuel distillates of. the type specified are produced ordinarily by the cracking of high boiling hydrocarbon oils in the vapor phase at temperatures of the order of 900 to 1290" F. While such distillates are reco'gmzed to be well adapted as fuels for automotive engines, due to their knock suppressing properties when burned in the cylinders of such engines, yet a considerable degree of care mustbe exercised in the refining thereof, usually immediately after manufacture, to prevent the formation of gumlike and color imparting compounds. These objectionable compounds are considered to be certain active members of the unsaturated hydrocarbons therein contained which unite with atmospheric oxygen to produce heavier and more complex compounds of higher boiling-range and greater molecular weights than those normally possessed by the oils in which they form.

To remove these undesirable gum-forming and color-imparting bodies from such oils, it has been customary heretofore to contact the oils while in a heated state with a finely divided solid adsorbent or catalyst such as fullers earth, acid treated clays, bentonite, silica gel and other analogous materials which possess the ability to adsorb or to catalytically accelerate the normal formation of, the undesired compounds, whereby to admit of the removal of the latter from the oils.

In such earlier processes, it has been necessary to employ relatively large quantities of the treating material to obtain the desired treating action with resulting high treating costs and, therefore, fundamentally it is an object of the present invention to provide an improved method of so treating cracked petroleum oils to obtain an effective removal of the aforesaid objectionable compounds and to accomplish this with the use of but a limited and comparatively reduced quantity of an extraneous non-petroleum treating agent to the general end of reducing treating costs.

In the attainment of this object, I have found that by heating the oil to a normally vaporizing but non-cracking temperature and by the employment of pressures thereon sufliciently high to prevent evolution of oil vapor, a very considerable degree of polymerizing of the undesuch as fullers earth.

, petroleum catalytic agent.

sirable unsaturated compounds present in theoil will take place independently of a treating agent merization is apparently a function of time, temperature and pressure but the action is comparatively slow and to secure the desired degree of treatment in eiiecting the formation of the polymers, the period of reaction is too long to provide for commercial operations. Therefore, to accelerate the process, I have found that by mixing with the oil a smallpercentage of the polymerized unsaturated compounds, while the oilis undergoing heating with the use of pressure in a still, the said polymerized compounds which contain the color-imparting and gum-producing bodies, and which may be referred to as petroleum polymers, apparently exert a catalytic action and accelerate the desired polymerizing reactions, especially when the oil undergoing treatment is maintained in the liquid phase.

It is therefore a further object of the invention to provide a continuous process for removing the aforesaid objectionable compounds from cracked unsaturated oils by passing a mixture of such oils and polymers through an elongated heating zone where the mixture is heated above the normal vaporizing temperatures of theoils, and coincidentally applying Dressure to the mixture sufiiciently high to prevent the evolution of vapors, whereby to maintain the mixture in the liquid, phase without any substantial cracking thereof. The mixture is maintained under such conditions of temperature and pressure for a sufficient period of time to secure the desired degree of polymerization of the objectionable bodies in the oils without the use of a non- In order to additionally accelerate the operation of my improved process and at the same time secure the desired degree of polymeriza-,

In other words, polytion, I pass the mixture of oils and polymerized bodies following their removal from the heating zone through a chamber containing fuller's earth orother equivalent treating agent. This is accomplished without materially reducing the pressure on the mixture so that said mixture is maintained in the liquid phase while in contact with the solid treating agent, the said contact serving to impart the final degree of polymerization to the oils of. the mixture undergoing treatment.

It is a still further object of the invention to continuously pass the treated oils following contact with said agent into a separating zone wherein the pressure on the oils is reduced to permit of the vaporization of the desired light and treated low boiling oils, the said vapors separating from the undesirable oils which have polymerized by the process into liquid like compounds of higher boiling range, the desired treated vapors being subsequently condensed and collected while a portion, at least, of the polymerized oils or polymers are returned to the inlet side of the heating zone or still for admixture with the incoming oils to be treated, the process in this particular operation being both continuous and, to a limited extent, cyclic.

For a further understanding of the invention,

reference is to be had to the following description and the accompanying drawing, wherein:

The figure is a diagrammatic view of apparatus employed by my improved process, the figure answering as a. .flow chart, indicating the paths of oil travel.

Referring more particularly to the drawing, the numeral l designates a tank or other container adapted for the reception of a cracked low boiling hydrocarbon oil having substantially the boiling range of ordinary gasoline. As above stated, this oil is preferably of the type containing high percentages of unsaturated'hydrocarbons andis produced by the cracking of high boiling hydrocarbon oils in the vapor phase at temperatures varying between 900 F. to 1200 F. The tank I is provided with a draw-off line 2 leading to the suction side of a high pressure pump 3. The discharge side of this pump is connected, by means of a line 4 with a heating coil 5 arranged in a furnace or still 6. A drum still may be used in lieu of the tube still disclosed, but the latter is preferred by reason of its greater thermal efii-.

ciency and continuous operation.

Also entering the suction side of the pump 3 r the coil 5, the mixture is maintained substantially in the liquid phase by the use of said pressures. The polymers present in the mixture appreciably accelerate the desired polymerizing reactions and apparently act catalytically in this respect with the result that a very considerable degree of polymerization of the undesirable bodies in the cracked oil takes place in the coil 5 alone.

However, to accelerate the operation and yet maintain its full effectiveness, the mixture discharged from the coil 5 by way of a pipe line 8 is, preferably without any material reduction in pressure, passed into a treating chamber 9, which is preferably an inclined heat insulated drum disposed beyond the confines of the still proper. In the lower portion of this drum, there is disposed a bed of a treating agent of the character defined above, fullers earth being ordinarily used in this connection. Since there has been no material reduction in pressure, the liquid mixture is passed through the bed of fullers earth, indicated at l0, so that by contact with the fullers earth, the final degree of polymerization is obtained. Preferably a pluralityof chambers 9 are employed having their inlets and outlets provided with suitable valves II and I2, whereby .said

chambers may be used alternately to provide for sustained operation of the process when fresh replacements of fullers earth are from time to time made.

Leading from the discharge ends of the chambers 9 is a pipe line 13 provided with a pressure reducing valve Hi, the line 13 being terminated within a' separating column l5. In this column there takes place a separation of the vapors of the treated oil from the polymerized higher boiling liquid compounds in which the aforesaid objectionable bodies are contained. Since the pressure within the column I5 is comparatively low, the free evolution of oil vapor takes place, the vapors of the desired treated oils being removed by way of an overhead line I6, which extends to a condenser l1 and a storage tank iii, in which the desired treated oils are finally received. The heavy gum-forming and color-imparting polymerized compounds collect in a substantially liquid form in the bottom of the separating zone and are removed by way of the valved outlet line I!) to a polymer storage tank 20, and the pipe line 1 leads from the tank '20 to the inlet side of the pump 3, whereby a portion, at least, of the polymers may be reused in the process as a reaction promoting agent. The line I is preferably equipped witha control valve 2|.

In the use of this process, it has been observed that when the mixture of polymers and cracked distillate is employed, the temperature rise in the fullers earth chamber is higher than when the polymers are omitted from the oils undergoing treatment. This temperature rise indicates that the process provides for a greater polymerizing reaction, since such reactions are largely exothermic. Also, with the employment of polymers in the mixture undergoing treatment, the color of the final distillate is materially improved over the corresponding color of the distillate when the polymers are not present. When the process is used without polymers, the final distillate usually possesses a color of approximately +1 2 Saybolt, whereas with the use of polymers, the average color of the treated distillate ranges between 17 and 18 Saybolt. The gravity of the distillates remains about constant varying usually between 4'7 and 50 A. P. I. while gum tests disclose in the finally treated distillates of either process approximately 40 to 6.0 mg. per 100-c. c. In a typical seeding run of 15 hours duration, the following data were obtainedz Charging stock (vapor phase cracked low boilin oi1)-89%.

Polymers1 1 Throughput-1700 barrels.

Still outlet temperature-570 F.

Fullers earth chamber outlet temperature- Pressure on charging pump1225 pounds.

Pressure on inlet of still-1200 pounds.

Pressure on clay chamber outlet-850 pounds.

During this operation a treated distillate was obtained having a gravity of 50.0, a 'color of +18 Saybolt, the distillate had an initial boiling point of 106 F., of the distillate boiled below 384 F. and an end point of 414 F. On analysis, this distillate contained 3.8 mg. of gum per c. c.

In all of these operations, I. have observed that the presence of the polymerized bodies in the oil undergoing treatment is advantageous, both in the matter of accelerating the operation and in insuring complete polymerization. The polymers may be used at low cost since they constitute nothing more than a by-product of the process.

e p a 9,180,894 By maintaining the oils in the liquid phase when in contact with the fullers earth, greatly prolonged life and activity of the 'clay is obtained over processes wherein vaporizedoiis are contacted with the clay and moreover the clay does not become so readily devitalized by adsorbed polymerized bodies. Theliquid phase operation serves to enable the oils to act as a solvent, washing the polymers from the clayso that the polymers may be trapped and separated in the column I.

While I have described certain pressure and temperature conditions of operation, it will be understood that these factors are subject to considerable variationwithout departing from the essential features of the process. I thereforeclaim as my invention all such modifications which may be said to fall fairly within the sco e of the following claim.

what is claimed is: v

' In a process for eifecting the removal of gumforming and color-imparting bodies from cracked low boiling unsaturated hydrocarbon oils, the step which consists in passing a solely petroleum'liquid mixture of such oils and hydrocarbon polymers containing the aforesaid bodies through a heating zone wherein the mixture is heated in the liquid phase to a temperature of the order of 600 F. while maintained under pressures of the order of 1200 pounds per square inch.

RUDOLPH C. TROM. 

